<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        div.lefttop {
            width: 0px;
            height: 150px;
            border-top-style: solid;
            border-top-color: red;
            border-top-width: 50px;
            border-left-style: solid;
            border-left-color: white;
            border-left-width: 50px;
            background-color: rgb(255, 255, 255);
            border-right-style: solid;
            border-right-width: 50px;
            border-right-color: white;
        }
    </style>
</head>

<body>
    <div class="lefttop">
    </div>
    <br>

</body>

</html>